Acquired thrombotic thrombocytopenic purpura is a rare and life-threatening disorder that causes blood clotting. Prior to the approval of Cablivi, patients underwent daily plasma exchange, which severely impacted their quality of life. Cablivi is an inhibitor of von Willebrand factor (vWF), which is a protein in the blood involved in hemostasis. Cablivi is an anti-vWF nanobody and Sanofi’s first Nanobody-based medicine to receive approval in the U.S. According to Sanofi, nanobodies are a novel class of proprietary therapeutic proteins based on single-domain antibody fragments that contain the unique structural and functional properties of naturally-occurring heavy chain only antibodies.

Olivier Brandicourt, Sanofi’s chief executive officer, said the approval of Cablivi provides a “much-needed treatment option” for people with aTTP.

“Cablivi marks the first U.S. approval in our newly formed rare blood disorders franchise, and we look forward to continuing to provide important medicines for people living with these very serious diseases,” Brandicourt said in a brief statement.

Patients with aTTP develop extensive blood clots in the small blood vessels throughout the body. These clots can cut off oxygen and blood supply to the major organs and cause strokes and heart attacks that may lead to brain damage or death. It is estimated that up to 20 percent of patients die from TTP episodes, with most deaths occurring within 30 days of diagnosis, Sanofi said. In the U.S., aTTP affects fewer than 2,000 adults each year.

Cablivi was approved based off clinical data that showed platelet counts improved faster among patients treated with Cablivi, compared to placebo. Additionally, treatment with Cablivi also resulted in a lower total number of patients with either aTTP-related death and recurrence of aTTP during the treatment period. Cablivi received FDA Fast Track designation and was evaluated under Priority Review, which is reserved for medicines that represent significant improvements in safety or efficacy in treating serious conditions.

Sanofi acquired Cablivi last year when the company snapped up Belgium-based Ablynxfor $4.8 billion. The newly-approved drug is expected to be available in the U.S. late in the first quarter. It will be sold at a list price of $270,000. Cablivi was approved in the European Union in August 2018.

Richard Pazdur, director of the FDA’s Oncology Center of Excellence and acting director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research, said Cablivi is a new treatment option that could reduce recurrences of a recurrence of aTTP.